Ski safety binding

ABSTRACT

A ski safety binding comprising, on the one hand, two anchoring supports intended to be fastened to the ski opposite each other and, on the other hand, two catch elements intended to be applied longitudinally to the ski boot, one alongside the other, each of said catch elements comprising two opposite push members movable axially and intended, one to engage with one of the anchoring supports and the other with the other anchoring support.

United States Patent Strub Dec. 9, 1975 SKI SAFETY BINDING 3,781,028 12/1973 Gertsch 280/1135 K Inventor: Rolf Strub Av. Gennecy 1249 3,834,723 9/1974 .Erlebach 280/1135 D Avully, Geneva, Switzerland E L F l Primary xaminer e0 riag ia [221 Flled 1974 Assistant Examiner-David M. Mitchell [21] App]. No.: 521,168 Attorney, Agent, or FirmAnthony J. Casella, Esq.

[30] Foreign Application Priority Data Nov. 21, 1973 Switzerland, 16404/73 ABSTRACT Oct. 10, 1974 Switzerland 13620/74 A skisafety binding p g on the one hand, two anchoring supports interided to be fastened to the ski [52] US. Cl. 280/ 1 1.35 pp each other and, on the other hand, two catch [51] Int Cl 2 A63: /086 elements intended to be applied longitudinally to the [58] Fieid S D 11 35 R ski boot, one alongside the other, each of said catch 280/11 35 M 11 5 A 5 5 elements comprising two opposite push members movable axially and intended, one to engage with one of 6 References Cited the anchoring supports and the other with the other anchoring support.

21 Claims, 8 Drawing Figures US. Patent Dec. 9, 1975 Sheet 2 of4 3 924369 ammmmmm US. Patent Dec.-9, 1975 Sheet 3 of4 3,924,869

US. Patent Dec. 9, 1975 Sheet 4 of4 3,924,869

I ma .wx \MR an m E \\\wwv\w wmwwiibfi H u. mm m wgjwfiggflim M {W d a SKI SAFETY BINDING Numerous safety bindings for skis are known which are intended automatically to disconnect the boot from the ski under certain circumstances, for instance when the skier falls. These safety bindings are generally adjustable so that the strength of the anchoring of the boot to the ski can be modified, this adjustment being effected on the one hand as a function of the weight of the skier and on the other hand as a function of his skill, that is to say as a function of the limits up to which the skier desires or is able to go before the release of the binding. Now, the lateral stresses, namely the stresses due to forces transverse to the longitudinal axis of the ski, are very substantial and if it is desired for the ski binding to withstand them without release it is necessary to adjust the binding so that its anchoring resistance is very high. While high anchoring resistance is indispensable for lateral and longitudinal forces (forces in the direction of the longitudinal axis of the ski), this is not, however, true in the case of twisting forces, that is to say the forces which occur when the leg of the skier pivots around its axis or around an axis substantially transverse to the plane of the ski. As a matter of fact, the bones of the skier cannot withstand these torsional effects and if the binding is adjusted to give sufficient anchoring resistance to absorb the lateral and longitudinal forces its anchoring resistance is also high for the torsional forces and it does not release or else it releases much too late, precisely when it should release immediately under the action of a relatively small force.

In order to overcome these drawbacks, the object of the present invention is a ski safety binding which is characterized by the fact that it comprises, on the one hand, two anchoring supports intended to be fastened to the ski opposite each other and each having a retain ing surface of convex shape and, on the other hand, two catch elements intended to be applied longitudinally to the ski boot, one alongside of the other, by the fact that each of these catch elements comprises two opposite push members movable axially, one of which is intended to come into engagement with the retaining surface of one of the anchoring supports and the other with the retaining surface of the other anchoring sup port in such a manner that the push members corresponding to each of the anchoring supports are arranged symmetrically with respect to the convexity of the retaining surface of said anchoring support, by the fact that the push members of each of the said catch elements each bear a piston which is movable against the action of a spring arranged between the said pistons, and by the fact that in each of the catch elements the assembly formed by the pistons and the spring arranged between them is movable longitudinally in a direction against the action of a spring which is weaker than the spring arranged between the pistons and is subjected to the action of a stop in the opposite direction.

The accompanying drawing shows, by way of example, two embodiments of the object of the invention.

FIG. 1 is a profile section in elevation of the first embodiment;

FIG. 2 is a plan view thereof in section;

FIGS. 3 and 4 are a profile section and a plan view in section respectively, showing an operating detail;

FIG. 5 is a plan view thereof with section showing another operating detail;

FIG. 6 is a section in elevation of a variant of a structural detail;

FIG. 7 is a profile section of the second embodiment;

FIG. 8 is a plan view with partial sections.

The safety binding shown in FIGS. 1 to 6 comprises two parallel tubes 1 and 2 arranged alongside of each other in the sole 3 of the ski boot 4. The tubes 1 and 2 are introduced respectively into channels provided for this purpose longitudinally in the sole 3 in which they are secured, for instance by gluing or in any other suitable manner.

Each of the tubes 1 and 2 contains a front piston 5 whose rod 6 is provided at its end with a push member 7 sliding in the corresponding end 8 of the tube and extending out of it, as well as a rear piston 9, facing the piston 5, its rod 10 having at its end a push member 11 which slides in a closure plug 12 screwed into the corresponding end of the tube which it closes. Like the push member 7, the push member 11 extends out of the closure plug 12 and protrudes beyond the sole 3 of the boot 4.

In each of the tubes 1 and 2 there is contained an open movable tubular cage 13 into which there are introduced the pistons 5 and 9 whose rods 6 and 10 pass through two openings 14 and 15 respectively provided in the end transverse walls 16 and 17 of said cage 13.

A compression spring 18 is provided in the cage 13 and rests against the pistons 5 and 9. This spring 18 is prestressed and pushes the pistons 5 and 9 against the walls 16 and 17 of the cage 13. The longitudinal movements of the cage 13 in the tube are limited in one direction by a shoulder 19 against which the end trans verse wall 16 of the cage strikes. In the opposite direction, the longitudinal movements of, the cage 13 are subjected to the action of a compression spring 20 located on the rod 10 and resting at one end against the end transverse wall 17 of the cage 13 and on the other end against the front end of the closure plug 12. The springs 18 and 20 are preferably selected as a function of the weight of the skier but in all cases the spring 18 must be definitely stronger than the spring 20.

In addition to the tubeQpiston-springs-push members assemblies described, the ski binding shown comprises two anchoring supports 21 and 22 fastened to the ski 23. t

The anchoring support 21 comprises a fastening plate 24, attached to the ski 23, for instance by screws (not shown) on which there is fastened a support 25 which has a vertical pin 26 on which there is rotatably mounted a ring 27 having a peripheral groove 28 intended to contain the end of the push members 7. The ring 27 is held axially on the pin 26 by a lock washer 29 fastened by a screw 30 engaged in the pin 26.

The anchoring support 22 comprises a fastening plate 31 secured to the-ski 23 by means of screws 32, this plate 31 having a vertical pin 33 on which there is rotatably mounted a ring 34 on l of the periphery of which there is a groove 35 intended to contain the end of the push members 11 while in the remaining there is an engagement incline 36, the groove 35 and the incline 36 being arranged one behind the other. The upper portion of the ring, 34 is shaped in such a manner as to form two operating legs 37 between which there is arranged a screw 38 which rests against a washer 39 and passes through the ring 34 to engage in the pin 33 and thus assure the holding fast of the ring 34.

The operation of the ski binding shown is as follows:

ENGAGEMENT AND DISENGAGEMENT The user places the boot 4 above the anchoring supports 21 and 22 and engages the push members 7 protruding at the front of the boot into the groove 28 of the ring 27 of the anchoring support 21. The push members 7 are thus held vertically by the edges of the groove 28 and are held in the plane of the groove by the fact that they are applied symmetrically with respect to the diameter of the groove and therefore the surface 41 (FIG. 2) of the bottom of the groove which is between them constitutes a retainer. The user then turns the ring 34 by means of the operating lugs 37 in such a manner as to bring the engagement incline 36 opposite the heel 40 of the boot 4. It is then sufficient to lower the heel 40 so as to push the push members 11 protruding to the rear of the boot against the engagement incline 36 and turn the ring 34 180 by means of the lugs 37, which brings the groove 35 opposite the heel 40 and at the same time permits the introduction of the push members 11 into the said groove 35. Here also the push members 11 are held vertically by the edges of the groove 35 while they are held in the plane of the groove by the fact that they are applied symmetrically with respect to the diameter of the groove, so that the surface 42 (FIG. 2) of the bottom of the groove which is present between the said push members constitutes a retainer.

As a result of the action of the springs 18 on the pistons 5 and 9, the piston rods 6 and 10 and therefore the push members 7 and 11 are constantly pushed back in opposite directions and the push members 7 and 11 apply themselves into the grooves 28 and 35 respectively. The springs 18 and the pistons 5 and 9 being in the cage 13, the spring 20 which acts against the end transverse wall 17 of the cage 13 does not affect the action of the spring 18 which, on its part, does not influence the action of the spring 20.

Due to the engagement of the push members 7 and 11 in the grooves 28 and 34, the boot 4 is securely held in place between the anchoring supports 21 and 22.

The release is effected in reverse manner to the manner of fastening.

AUTOMATIC RELEASE a. Lateral force Let us assume a transverse course acting on the binding in the direction indicated by the arrow 43 (FIG. 2). The push members 7 and 1 1 which are on the same side as the arrow 43 are forced against the surfaces 41 and 42 of the grooves 28 and 35 respectively, which will have the effect of moving them in opposite directions to each other against the action of the spring 18 on which they act via the rods 6 and 10 and pistons 5 and 9 respectively. At the same time, the push members 7 and 11 which are on the opposite side will expand to release themselves from their respective grooves. If the transverse force acting on the binding is greater than the force of the spring 18, the said push members 7 and 11 may go beyond the retainer formed by the surfaces 41 and 42 of the grooves 28 and 35 and free themselves from said grooves, which will disconnect the boot 4 from the ski 23. It will be noted that the springs 20 do not act during this type of release.

b. longitudinal force Let us assume a longitudinal force which has the effect of tilting the boot 4 in the direction indicated by the arrow 44 (FIG. 3). The push members 7 remain applied in the groove 28 while the push members 11 are forced against the upper edge of the groove 34 following the profile of said groove, which movement will have the effect of pushing the push members 11 slightly back towards the inside of the tubes 1 and 2, against the action of the springs 18. If the force is sufficiently great to overcome the force of the springs 18, the push members 11 will retract sufficiently to be capable of freeing themselves from the groove 34 (FIGS. 3 and 4), which will free the back of the boot 4 and therefore the front of the boot since the push members 11 no longer exert any retaining action. It will be noted that the springs 20 do not operate in the case of this release.

0. Twisting force Let us assume here that the boot 4 pivots in the direction indicated by the arrow 45 (FIG. 5) while the ski 23 remains in its line. The push member 7 which is on the outside of the curve will be forced in the groove 28 towards the inside of the curve while the push member 1 1 which is opposite it will be similarly disengaged from the groove 34 towards the outside of the curve. The movement of the push member 7 will affect the rod 6, the piston 5, the spring 18, the piston 9, the transverse wall 17 of the cage 13, and the spring 20. Now, as previously indicated, the spring 18 is definitely stronger than the spring 20. Accordingly, the assembly consisting of the piston 5 spring 18, piston 9, transverse wall 17 and cage 13 will move as a unit and it will be the spring 20 which offers the resistance to the force exerted on the push member 7, while the spring 18 plays a minimal part. If the force imposed on the push member 7 is greater than the force of the spring 20, the push member 7 can go beyond the tension formed by the surface 41 of the groove 28 and free itself from the latter, towards the inside of the curve, while the push member 11 which is opposite it will at the same time free itself from the groove 35, towards the outside of the curve. During this movement, the push member 7 which is on the inside of the curve will free itself fromthe groove 28 and will not play any part, while the push member 11 which is opposite it will slide along the groove 35 without effecting any retention since it is subject to the action of the spring 18 which is definitely stronger than the spring 20 on which the push member 7 located on the outside of the curve acts. The boot 4 can thus free itself from the ski and it will be noted that the springs 18 participate minimally in this release.

From the foregoing it is clear that in case of release under lateral or longitudinal force, it is only the springs 18 which act while in the case of release under torsional force only the springs 20 enter into action. As the springs 18 are definitely stronger than the springs 20, the anchoring resistance will be substantially greater for lateral and longitudinal forces than it is for torsional forces. One will therefore have a safety binding which automatically differentiates between the forces undergone and releases more easily under torsional forces'than under lateral and longitudinal forces.

Of course the arrangement of the springs and push members may be reversed, without any change in the operation of the binding. Similarly, the anchoring supports 20 and 21 may be reversed.

As described, the tubes 1 and 2 with their respective push members, cages, and springs, are secured in the sole 3 of the shoe 4. This arrangement however is not limitative and the tubes can easily be placed in a suitable housing or the like adapted to be fastened below the boot. Alternatively, the tubes 1 and 2 may also be fastened individually below the boot, for instance by means of clamps screwed in the sole 3.

As has been seen, the boot is borne entirely by the push members 7 and 1 1. Therefore, if the plates 24 and 31 supporting the rings 27 and 34 are imparted suffrcient height, the boot will be fully suspended between the anchoring supports 21 and 22. This arrangement is shown in FIGS. 1 and 3 from which it can be noted that there is an appreciable space 46 between the sole 3 and the ski 23. This facilitates the hooking of the boot between the anchoring supports 21 and 22, particularly when the sole 3 is covered with a layer of compacted snow. Furthermore, there is no danger of the rubbing of the sole against the ski interfering with or retarding the release of the fastener, particularly under the effect of torsional forces. However, this arrangement is not limitative and the height of the anchoring supports may be such that the boot rests against the ski.

In accordance with a variant, the rings 34 and/or 27 may be elastic along their axis. FIG. 6 shows such a variant applied to the anchoring support comprising the engagement incline. The ski 23 as well as the sole 3 of the shoe 4 and the push members 11, the latter being about to release, can be noted. The anchoring support shown comprises a fastening plate 47 secured to the ski 23 and having a vertical pin 48 on which there is rotatably engaged a ring 49 which is provided, over 180 of its periphery, with a groove 50 intended to contain the end of the push members 11 and, over the remaining 180, an engagement incline 51, the groove 50 and the engagement incline 51 being arranged one as a continuation of the other. In the ring 49 there is housed an elastic element formed of spring washers 52 resting on the one side against the bottom 53 of the ring 49 and on the other side against the head of a screw 54 engaged in the pin 48 and assuring the holding fast of the ring. Thus when the push members 11 are forced against the upper edge of the groove 50 under the action of a longitudinal force having the effect of tilting the boot in the direction indicated by the arrow 55, they drive the ring 49 against the action of the spring washers 52 before retracting to free themselves from the groove 50. This arrangement imparts additional flexibility to the bindmg.

The safety binding shown in FIGS. 7 and 8 comprises an elongated housing 101 intended to be fastened removably below the sole of the ski boot, shown schematically in 104, this removable attachment being effected in any suitable manner, for instance by means of conventional fast-closing clamps.

In the housing 101 two longitudinal channels 102 and 103 are arranged, one alongside of the other. In each of said channels 102 and 103 there are provided a front piston 105 whose rod 106 is provided at its end with a push member 107 extending out of the housing 101 and sliding in a sleeve 108 fastened in the corresponding end of the channel, and a rear piston 109 facing the piston 105 and whose rod 110 is provided at its end with a push member 111 also extending out of the housing 101 and sliding in a closure plug 112 fastened, for in stance force-fitted, in the corresponding end of the channel, which it closes. The arrangement of the housing 101 and of the push members 107 and 111 is such that the said push members protrude from the sole of the boot 104.

The longitudinal movements of each of the push members 107 are limited in one direction by a shoulder 113 arranged in the channel and against which the pis- 6 ton 105 strikes. In the opposite direction, each of the pistons 105 comes against a ring 114 which is movable in the channel and has an end 115. The head 116 of a screw 117 whose shank slides through the end 115 of the ring 114 is introduced into said ring. The head 1 16 of the screw 117 can best move longitudinally in the ring 114 between the 'end 115 and the piston 105. Over the shank of the screw 117 there is engaged a compression spring 118 one end of which rests against the end 115 of the ring 114 and the other end of which is applied against a stop 119 screwed on the screw 117. The spring 118 is thus compressed between the end 115 and the stop 119, and its tension can be modified by screwing or unscrewing the stop 119 on the screw 117.

On the side opposite the spring 118, the stop 119 is in contact with the piston 109 and. the latter is trapped between the stop 119 and a sleeve 120 which is movable longitudinally in the channel and engaged on the rod 110. The movements of the sleeve 120 are limited, on the side of piston 109, by a shoulder 121 provided in the channel and, on the side opposite the piston 109, the sleeve 120 rests against a compression spring 122 engaged on the rod 110, the other end of which is applied against a ring 123 coaxial to the rod 110 and retained by the closure plug 112. The springs 118 and 122 are preferably selected as a function of the weight of the skier but, in all cases, the springs 118 must be definitely stronger than the springs 122.

In addition to the structures described, the ski bind ing shown has two anchoring supports 124 and 125 fastened to the ski 126 opposite each other, for instance by means of screws, not shown. The anchoring support 124 has a generally cylindrical convex retaining surface 127. The anchoring support 125 also has a generally cylindrical inclined convex retention surface 128, this surface 128 being extended by a convex engagement plane inclined in opposite direction and also of generally cylindrical shape. The retention surfaces 127 and 128 are inclined towards each other and, instead of the generally cylindrical shape, they may each be formed of two planes forming an inclined dihedral, the edges of these two dihedrals being inclined towards each other.

The operation of the binding shown is as follows:

HOOKING The housing 101 being fastened to the ski boot, the said housing is placed on the ski 126 so as to bring the push members 107 protruding towards the front of said housing into engagement with the convex inclined retention surface 127 of the anchoring support 124. The push members 111 protruding towards the rear of the housing 101 are then applied onto the engagement plane 130 of the anchoring support 125 and a vertical pressure is exerted on the heel of the boot. As a result of the inclination of the engagement incline, the push members 111 are pushed back towards the inside of the housing 101; this push has a repercussion on the rods 110, the pistons 109, the stops 119 and the springs 1 l8 retained by the rings 114 which are applied against the pistons 105 which are stopped by the shoulders 113. As a result of the sliding of the screw 117 in the end 115 of the ring 114, the springs 118 can be compressed be tween the rings 114 and the stops 119 and the movement of the push members 111 therefore takes place against the action of the springs 118. When the push members 111 arrive at the retaining surface 128, they can move in opposite direction due to the inclination of said retaining surface, under the action of the springs 118. When the housing 101 is applied to the ski, the push members 107 and 11 1, pushed back by the springs 118, apply themselves against the retaining surfaces 127 and 128 respecticely. Due to the inclination of the said surfaces and their convexity, the push members 107 and 111 effect the vertical holding as well as the transverse and longitudinal holding of the housing 101 on the ski, and therefore of the ski boot which is fastened to said housing.

Since the ski boot is removably fastened to the housing 101, it is not necessary to provide any procedure for the freeing of the latter during the automatic release.

AUTOMATIC RELEASE a. Lateral force Let us assume a transverse force acting on the fastener in the direction indicated by the arrow 129 (FIG. 8). The push members 107 and 111 located on the same side as this force are forced against the retaining surfaces 127 and 128 of the anchoring supports 124 and 125 respectively, which will have the effect of moving them in direction opposite each other against the action of the spring 1 18 on which they act respectively via the rods 106 and 110, the pistons 105 and 109, the ring 114 and the stop 119, the compression of the spring 118 being made possible as the result of the sliding of the screw 117 in the bottom 115 of the ring 114. At the same time, the push members 107 and 111 which are on the opposite side will tend to free themselves from the retaining surfaces 127 and 128. If the transverse force acting on the binding is greater than that of the stressed spring 118, the said push members 107 and 111 can go beyond the stop formed by the surfaces 127 and 128 and free themselves from the latter, which will disconnect the housing 101 from the ski 126. It will be noted that the springs 122 which are held by the sleeve 120 resting against the shoulder 121 do not take part during this type of release.

b. Longitudinal force Let us assume a longitudinal force having the effect of tilting the ski boot in the direction indicated by the arrow 131 (FIG. 7). The push members 107 come to rest applied against the retaining surface 127 while the push members 111 are forced towards the upper portion of the retaining surface 128, while following the profile of the latter. Due to the inclination of the retaining of the retaining surface 128, this movement will have the effect of pushing the push members 111 back towards the inside of the housing 101 against the action of the springs 118. If the force 131 is sufficiently great to overcome the force of the springs 118, the push members 111 retract sufficiently to be able to free themselves from the retaining surface 128, which will liberate the rear of the housing 101 and, therefore, the front of the latter since the push members 111 no longer exert any retaining action. It will be noted that the springs 122 which are retained by the sleeve 120 resting against the shoulder 121 do not participate in this release.

0. Torsional force Let us assume here that the boot pivots in the direction indicated by the arrow 132 (FIG. 8), while the ski remains in the same line. The push member 107 which is on the outside of the curve will be forced against the retaining surface 127 towards the inside of the curve while the push member 111 which is opposite it will be freed similarly from the retaining surface 128 towards the outside of the curve. The movement of the push member 107 will affect the rod 106, the piston 105, the ring 114, the spring 118, the stop 119, the piston 109, the sleeve 120, the spring 122 which is retained by the ring 123. Now, as previously stated, the spring 118 is definitely stronger than the spring 122. It follows that the assembly consisting of piston ring 114 spring 1 18 piston 109 sleeve will move as a unit against the action of the spring 122 and that it is the latter which will offer the resistance to the force exerted on the push member 107 which is on the outside of the curve, the spring 118 serving substantially as a rigid element. If the force imposed on the said push member 107 is greater than the force of the spring 122, the push member 107 can exceed the retention formed by the retaining surface 127 and free itself from the latter towards the inside of the curve, while the push member 111 which is opposite it will simultaneously free itself from the retaining surface 128 towards the outside of the curve. During this movement, the push member 107 which is on the inside of the curve will free itself from the retaining surface 127 and will not play any role, while the push member .111 which is opposite it will slide along the retaining surface 128 without effect ing any retention whatsoever since it is subjected to the action of the spring 118 which is definitely stronger than the spring 122 acting on the push member 107 which is on the outside of the curve. The housing 101 and therefore the ski boot can thus be disconnected from the ski 126 and it will be noted that the springs 118 do not participate in this release.

From the foregoing it is seen that in the case of release under lateral or longitudinal force, only the springs 118 act. On the other hand, in the case of release under torsional force, only the springs 122 enter into action. As the springs 118 are definitely stronger than the springs 122, the anchoring resistance will be substantially greater for lateral and longitudinal forces than for torsional forces. The binding described there-- fore automatically differentiates between the forces experienced and releases more easily under torsional forces than under lateral and longitudinal forces.

Of course the arrangement of the springs and push members may be reversed without in any way changing the operation of the binding. Similarly, the anchoring supports 124 and 125 may be reversed.

The housing 101 described is adapted to be fastened to the ski while the boot is removably held on said housing. This arrangement is not limitative and the housing in question may be integrated with the boot, in which case one of the anchoring supports will preferably be provided with means permitting the manual disconnecting of the binding.

What is claimed is:

1. Safety ski binding, characterized by the fact that it comprises on the one hand two anchoring supports intended to be fastened to the ski opposite each other and each having a retaining surface of convex shape in a horizontal plane, and on the other hand two catch elements intended to be attached longitudinally to the ski boot, one alongside the other, by the fact that each of these catch elements comprises an elongate channel two opposite push members movable axially within said channel and intended to extend from said channel, one to come into engagement with the retaining surface of one of the anchoring supports and the other with the retaining surface of the other anchoring support so that the push members corresponding to each of the anchoring supports are arranged symmetrically with respect to the convexity of the retaining surface of the said anchoring support, by the fact that the push members of each of said catch elements each bear a piston which is movable within said channel against the action of a first spring arranged between said pistons, and by the fact that in each of the catch elements the assembly formed by the pistons and the first spring arranged between them is movable longitudinally in one direction against the action of a second spring arranged within said channel, which is weaker than said first spring, and said assembly is subject to the action of a stop, fixed within said channel, in the opposite direction.

2. Binding according to claim l,'characterized by the fact that said pistons are movable in a cage, said first spring is housed in the cage and pushes each of the said pistons back against a corresponding transverse wall of the cage, and by the fact that the cage is movable longitudinally in one direction against the action of said second spring and is retained in the opposite direction by a shoulder against which one of the transverse walls of said cage strikes.

3. Binding according to claim 1, wherein said stop comprises a shoulder which abuts one of said pistons to retain the assembly in said opposite direction.

4. Binding according to claim 3, characterized by the fact that said second spring is coaxial to the push member opposite the piston retained by the shoulder of the channel, and by the fact that this spring rests on the one hand against a guide piece of the said push member fastened in the channel and on the other hand against a stop which is movable in the channel and is retained in the same direction as said one piston by a second shoulder arranged in said channel.

5. Binding according to claim 4, characterized by the fact that the spring arranged between the pistons is engaged on a rod one end of which is fastened to a stop resting against one of the pistons and the other end of which is retained and slides in a ring resting against the other piston.

6. Binding according to claim 5, characterized by the fact that the length of the rod is variable.

7. Binding according to claim 6, characterized by the fact the rod is screwed into the stop.

8. Binding according to claim 2, characterized by the fact that each of the channels comprises a tube in which the push members and the cage slide.

9. Binding according to claim 8, characterized by the fact that the spring acting on the cage is coaxial with one of the push members and rests on the one end against one of the transverse walls of the cage and on the other end against a guide part of the said push member which is rigidly connected with the tube.

10. Binding according to claim 2, characterized by the fact that the spring which is housed in the cage and acts on the pistons of the push members is prestressed.

11. Binding according to claim 1, characterized by the fact that the catch elements are fastened below the sole of the ski boot and by the fact that the push members protrude past each end of the boot.

12. Binding according to claim 1, characterized by the fact that the catch elements are integrated in the 10 sole of the ski boot and by the fact that the push members protrude beyond each end of the boot.

13. Binding according to claim 1, characterized by the fact that each of the anchoring supports comprises an inclined retaining surface which is generally cylindrically shaped in a horizontal plane, and by the fact that the said retaining surfaces are inclined upwardly towards each other.

14. Binding according to claim 1, characterized by the fact that each of the anchoring supports comprises an inclined retaining surface formed of two planes forming a dihedral angle in a horizontal plane, and by the fact that the upper edges of the said planes are inclined toward each other.

15. Binding according to claim 13, characterized by the fact that one of the anchoring supports comprises an engagement incline of convex shape extending from the retaining surface and inclined in opposite direction.

16. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports comprises a ring mounted for rotation on a pin fasten ed to the ski, and said retaining surface comprises a peripheral groove on said ring has been inserted to positively relate the groove to the retaining surface; intended for the engagement of the push members of the catch elements.

17. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports comprises a ring mounted for rotation on a pin fastened to the ski, and said retaining surface comprises a groove in the periphery of said ring bearing over intended for the engagement of the push members of the catch elements, with the remaining 180 of the periphery of said ring being an incline for the engagement of said push members, the groove and the incline being arranged one behind the other.

18. Binding according to claim 16, characterized by the fact that the ring bears at least one operating lug.

19. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports is mounted to the ski by elastic means which allow the support to resiliently move vertically relative to the plane of the ski.

20. Binding according to claim 19, characterized by the fact that the anchoring support comprises a ring, said retaining surface comprises a groove provided over at least a portion of the periphery of said ring intended for the engagement of the push members of the catch elements, said ring being mounted by said elastic means for rotation on a pin fastened to the ski and extending into an axial recess of said ring in which there are arranged spring washers coaxial with the pin and resting on one side against the bottom of said recess and on the other side against a retaining part which is rigidly connected with the pin. and assures the holding of the ring on it.

21. Binding according to claim 16, characterized by the fact that the anchoring supports are fastened to the ski at such a height that the ski boot is entirely sus' pended between said anchoring supports when the push members of the catch elements are engaged in the grooves of the anchoring supports. 

1. Safety ski binding, characterized by the fact that it comprises on the one hand two anchoring supports intended to be fastened to the ski opposite each other and each having a retaining surface of convex shape in a horizontal plane, and on the other hand two catch elements intended to be attached longitudinally to the ski boot, one alongside the other, by the fact that each of these catch elements comprises an elongate channel two opposite push members movable axially within said channel and intended to extend from said channel, one to come into engagement with the retaining surface of one of the anchoring supports and the other with the retaining surface of the other anchoring support so that the push members corresponding to each of the anchoring supports are arranged symmetrically with respect to the convexity of the retaining surface of the said anchoring support, by the fact that the push members of each of said catch elements each bear a piston which is movable within said channel against the action of a first spring arranged between said pistons, and by the fact that in each of the catch elements the assembly formed by the pistons and the first spring arranged between them is movable longitudinally in one direction against the action of a second spring arranged within said channel, which is weaker than said first spring, and said assembly is subject to the action of a stop, fixed within said channel, in the opposite direction.
 2. Binding according to claim 1, characterized by the fact that said pistons are movable in a cage, said first spring is housed in the cage and pushes each of the said pistons back against a corresponding transverse wall of the cage, and by the fact that the cage is movable longitudinally in one direction against the action of said second spring and is retained in the opposite direction by a shoulder against which one of the transverse walls of said cage strikes.
 3. Binding according to claim 1, wherein said stop comprises a shoulder which abuts one of said pistons to retain the assembly in said opposite direction.
 4. Binding according to claim 3, characterized by the fact that said second spring is coaxial to the push member opposite the piston retained by the shoulder of the channel, and by the fact that this spring rests on the one hand against a guide piece of the said push member fastened in the channel and on the other hand against a stop which is movable in the channel and is retained in the same direction as said one piston by a second shoulder arranged in said channel.
 5. Binding according to claim 4, characterized by the fact that the spring arranged between the pistons is engaged on a rod one end of which is fastened to a stop resting against one of the pistons and the other end of which is retained and slides in a ring resting against the other piston.
 6. Binding according to claim 5, characterized by the fact that the length of the rod is variable.
 7. Binding according to claim 6, characterized by the fact the rod is screwed into the stop.
 8. Binding according to claim 2, characterized by the fact that each of the channels comprises a tube in which the push members and the cage slide.
 9. Binding according to claim 8, characterized by the fact that the spring acting on the cage is coaxial with one of the push members and rests on the one end against one of the transverse walls of the cage and on the other end against a guide part of the said push member which is rigidly connected with the tube.
 10. Binding according to claim 2, characterized by the fact that the spring which is housed in the cage and acts on the pistons of the push members is prestressed.
 11. Binding according to Claim 1, characterized by the fact that the catch elements are fastened below the sole of the ski boot and by the fact that the push members protrude past each end of the boot.
 12. Binding according to claim 1, characterized by the fact that the catch elements are integrated in the sole of the ski boot and by the fact that the push members protrude beyond each end of the boot.
 13. Binding according to claim 1, characterized by the fact that each of the anchoring supports comprises an inclined retaining surface which is generally cylindrically shaped in a horizontal plane, and by the fact that the said retaining surfaces are inclined upwardly towards each other.
 14. Binding according to claim 1, characterized by the fact that each of the anchoring supports comprises an inclined retaining surface formed of two planes forming a dihedral angle in a horizontal plane, and by the fact that the upper edges of the said planes are inclined toward each other.
 15. Binding according to claim 13, characterized by the fact that one of the anchoring supports comprises an engagement incline of convex shape extending from the retaining surface and inclined in opposite direction.
 16. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports comprises a ring mounted for rotation on a pin fastened to the ski, and said retaining surface comprises a peripheral groove on said ring has been inserted to positively relate the groove to the retaining surface; intended for the engagement of the push members of the catch elements.
 17. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports comprises a ring mounted for rotation on a pin fastened to the ski, and said retaining surface comprises a groove in the periphery of said ring bearing over 180* intended for the engagement of the push members of the catch elements, with the remaining 180* of the periphery of said ring being an incline for the engagement of said push members, the groove and the incline being arranged one behind the other.
 18. Binding according to claim 16, characterized by the fact that the ring bears at least one operating lug.
 19. Binding according to claim 1, characterized by the fact that at least one of the anchoring supports is mounted to the ski by elastic means which allow the support to resiliently move vertically relative to the plane of the ski.
 20. Binding according to claim 19, characterized by the fact that the anchoring support comprises a ring, said retaining surface comprises a groove provided over at least a portion of the periphery of said ring intended for the engagement of the push members of the catch elements, said ring being mounted by said elastic means for rotation on a pin fastened to the ski and extending into an axial recess of said ring in which there are arranged spring washers coaxial with the pin and resting on one side against the bottom of said recess and on the other side against a retaining part which is rigidly connected with the pin and assures the holding of the ring on it.
 21. Binding according to claim 16, characterized by the fact that the anchoring supports are fastened to the ski at such a height that the ski boot is entirely suspended between said anchoring supports when the push members of the catch elements are engaged in the grooves of the anchoring supports. 